Doctors prescribe you a drug because they believe it is scientifically proven to be effective, and to be safe. They get their proof from trials on the drug. But - as researchers remind us this week - the trials are paid for by the manufacturer, and that almost guarantees a positive outcome every time. When researchers from the Children's Hospital in Boston, USA, reviewed 546 drug trials, they found that those that were paid for by the manufacturer produced a positive outcome in 85 per cent of cases. However, independent trials, funded by government agencies, produced a positive result in only half of the studies. Worse, drug companies are under no obligation to publish any study after the drug has been licensed - which means a poor result can be put into the filing cabinet, and forgotten. Instead of hiding the study for all time, the drug company might instead prefer to delay publication for several years so as not to dampen revenues in the first years after the drug's launch. (Source: Archives of Internal Medicine, 2010; in print).